The present invention relates to fluoroquinolone carboxylic acid molecular crystals. In particular, present invention relates to a molecular crystal of (R)-(+)-7-(3-amino-2,3,4,5,6,7-hexahydro-1H-azepin-1-yl)-1-cyclopropyl-8-chloro-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid.
Synthetic antimicrobial agents such as nalidixic acid, piromidic acid, and the like are known as drugs for curing infectious diseases caused by Gram negative microorganisms. They exhibit, however, only deficient effects on intractable diseases such as pseudomoniasis and the like.
On the other hand, quinolone carboxylic acid derivatives substituted with a fluorine atom at 6 position, such as norfloxacin, ofloxacin, and ciprofloxacin, or quinolone carboxylic acid derivatives substituted with a chlorine atom at 8 position have been developed (Japanese Patent Laid-open (ko-kai) Nos. 225181/1986, 90183/1989) and clinically used because of their strong antimicrobial activity.
These conventional synthetic antimicrobial agents had defects of insufficient absorptivity in a living body, providing only low bioavailability, and of a low antimicrobial activity against Gram positive microorganisms.
Therefore, development of antimicrobial agents having strong antimicrobial activity against both Gram positive and Gram negative microorganisms, including resistant bacteria, and superior absorptivity in living bodies has been desired.
Active pharmaceutical agents (“APIs”) are often organic molecules, which can exist in different organic crystal forms depending on their processes of manufacture. Such different molecular crystal forms can have practical influence on pharmaceutical compositions comprising these APIs, such as their processability, physical and chemical properties, stability, etc.
Therefore, it is desirable to provide a molecular crystal form of the API that has advantageous properties. In particular, it is very desirable to provide a molecular crystal form of a fluoroquinolone carboxylic acid that has advantageous properties for the manufacture of novel anti-infective pharmaceutical compositions.